Putative hybrids between vars. foliosa and monocephala are highly fertile and show a gradual transition from discoid to radiate morphology, including "elongation of the corolla, changes in the corolla morphology from actinomorphic to bilabiate to radiate, and a reduction to subsequent loss of the androecium in the outer florets...trends observed throughout the putative hybrid swarm" (J. F. Hughes and G. K. Brown 1994).